The Palestinian minister in charge of the struggle against the Israeli separation wall and settlements died Wednesday shortly after a physical confrontation with Israeli soldiers in a village just outside of Ramallah.

Witnesses told the Palestine Monitor they saw an officer from the Border Police head-butt Minister Ziad Abu Ein before striking him in the chest. Others said Abu Ein was hit the butt end of a rifle and kicked.

Abu Ein was taking part in a symbolic olive tree planting action, part of a coordinated struggle of the Palestinian villages of Turmusiya and Al Mugheir against the illegal settlement outpost of Adei Ad, which has stolen vital farming land from both.

Abu Ein and a group of nearly 100 demonstrators were confronted by a group of nearly 30 Israeli soldiers and border police. An image published by Reuters news agency shows a Border Policemen grasping Abu Ein by the neck. Minutes after the confrontation, the minister reportedly fell to the ground clasping his chest. He died on the way to the hospital.

It is not yet clear what caused his death.

Palestinian President Mahmoud Abbas described the attack as “a barbaric act which we cannot be silent about or accept.” Abbas announced three days of national mourning, threatening to cancel the Palestinian Authority’s security coordination with Israel. He said he would take “necessary steps” after an investigation into Abu Ein’s death is carried out.

Shortly before his death, Abu Ein spoke to a group of television reporters while standing amidst a group of Israeli soldiers.

“This is the terrorism of the occupation, this is a terrorist army, practicing its terrorism on the Palestinian people,” he told the official Palestine TV. “We came to plant trees on Palestinian land, and they launch into an attack on us from the first moment. Nobody threw a single stone.”

Stores and restaurants around Ramallah closed Wednesday afternoon in protest over the minister’s death.